Nick Clegg tonight laid out proposals to his party for a new structure that would enable the Liberal Democrats to keep a distinctive voice while in coalition.

The party high command have modified the demands of Simon Hughes, the new deputy leader, to appoint independent spokespeople to shadow every government department. Instead, in proposals put to the party's MPs, a series of small backbench select committees will be set up, spanning several government departments, with one chair and vice-chair chosen to orchestrate policy development and Lib Dem questions in the house.

The chairs will be appointed by Clegg and are not supposed to be the committees' only spokesperson since they could come to rival the coalition's official appointment. The chair and vice-chair will represent both MPs and Lords.

There is also a suggestion those committees will have access to government departments.

The proposals will unnerve many Conservative MPs who have been lobbying their party for the reinstatement of their party's backbench policy committees, in a similar bid to retain Tory distinctiveness while in coalition.

If the Lib Dems accept the proposal, party chiefs think it could only come into effect by the end of next week, after George Osborne delivers the emergency budget on Tuesday. Senior Lib Dems know that event could cause a strain on their colleagues since it may include an increase in VAT, which the party campaigned against in the general election.

Hughes had wanted the Lib Dems to have shadow spokesmen in government departments in which they are not represented including Defra, International Development, and Wales. He is also keen that the Speaker choose Lib Dems to speak after the coalition and Labour in the Commons.

The party has already been exerting its independence outside of government, with Hughes saying on Monday he would be likely to have difficulty accepting a decision by the coalition government to increase tuition fees.

Though the coalition document allows Lib Dems — committed to scrapping the policy altogether after six years — to abstain should they be asked to vote through an increase in the fees, former leader Sir Menzies Campbell has already said he would be unable to do that and would have to vote against it. Others have said they would be unable to vote through the government's academies bill.

Lib Dem sources within government have been making it clear to backbenchers that disagreements with the coalition will weaken their collective ambition to win a referendum on AV. If the Lib Dems frequently erupt in disagreement, the argument goes, the public will be less inclined to accept a change that could make coalitions more, not less, likely.